Safety-tank drill



March 21, 1961 l. LA DELLE HEIDEMAN 2,975,660

SAFETY-TANK DRILL INVENTOR.

United States Patent 2,975,660 SAFETY-TANK DRILL Irvin La Delle Heideman, Glen Ellyn, Ill., assignor to Pettibone Mulliken Corporation, a corporation of Delaware Filed Oct. 8, 1958, Ser. No. 766,024 Claims. (Cl. 77-13) There are times when it is desirable to cut a hole in the roof of a huge storage tank such as is used for gasoline or the like at refineries or distribution centers. For example, if it is desired to replace an existing vent valve of ordinary type with one controlled by a pilot valve, it is necessary to provide a separate hole for the connection to the pilot valve. The pilot valve should be subject to the pressure generally prevailing inside of the tank, not that in the main valve aperture, which varies when the main-valve opens. Therefore the pilot valve connection may not merely be led off from the existing main valve connection.

Because explosive mixtures of gasoline fumes and air may be found within a gasoline storage tank, it is apparent that cutting a hole in such a tank presents a severe problem. There is likely to be an explosive mixture of gasoline fumes and air within the tank, and a tremendous explosion could result from a sprak or even from the hot metal present during drilling or cutting the hole. Furthermore, as the hole is cut, escaping gases could present a new hazard.

According to the present invention, the cutting of the hole is made completely safe-by applying inside of the tank, where the hole is to be cut, a protective hood which may be filled with an inert gas or grease to protect the gases within the tank quite thoroughly from the possibility of contact with a spark or hot metal. With the preferred apparatus, the hood may be applied through the main valve throat and'will automatically be positioned in alignment for the cutting tool, which is carried by the same apparatus.

Additional objects and advantages of the invention will be apparent from the following description and from the drawings.

Designation of figures Figure 1 is a view showing a fragment of the tank in which a hole is to be cut, with the apparatus of this invention applied to it. The apparatus is shown largely from the side, some parts being broken away for clarity.

Figure 2 is a fragmentary view taken at right angles to the apparatus in Fig. 1, showing seal plates laid across the opening of the main valve throat.

Figure 3 is a view showing a punch secured in the chuck of Fig. 1, for use before the drilling operation starts.

General description The invention is shown as applied to a large storage tank having a roof 10 provided with a main valve throat 11 having a collar 12 at its top from which it may be assumed that the main valve, being replaced by a new type operated by a pilot valve, has been removed.

According to the present invention, a main frame or beam 13 carries an arm 14 in the form of a bell crank lever which is pivotally carried by a standard 16 secured to the beam 13. Beam 13 is laid across the collar 12 after first manipulating the assembly to slip arm 14 through the throat 11 and into the tank. Screws 15 securing standard 16 to beam 13 can be removed if separate insertion of arm 14 should unexpectedly be found necessary.

this time.

The beam 13 is secured to collar 12 by screws 17.-

press a cup shaped hood 22 firmly against the tank roof 1 10. Gas of the tank can be excluded from the hood 22 by its having been preliminarily filled with an excess of grease, so that this grease is squeezed out as the hood is raised against the roof. 7

The drill press assembly including and carried by a screw 26 is now applied to beam 13 which receives it in a position to be aligned with hood 22. The feedscrew 26 may be turned by a handle 27 and has a threaded engagement with the beam 13 so that as turned it is advanced toward the hood 22. A drill spindle 28 is journalled in the feed screw 26 and is turned by a handle 29. A chuck 31 is carried by spindle 28 and rotated by it. In Fig. 1, the chuck 31 is seen carrying a hole saw assembly 33, the leading element of which is a twist drill 34. After the twist drill 34 has drilled its small hole through the roof 10, it acts as a centering journal while cylindrical saw 36 saws a large hole through the roof 10.

During the drilling and sawing operation, a ring 38, sealed to the roof 10 in any suitable manner as by a clay ring 39, may retain a pool of quenching medium such as relatively inert liquid to prevent any stray combustible gas mixtures outside of the tank from coming into contact with hot surfaces or chips. The liquid may desirably be suitable for cooling and lubricating the drilling and sawing operation, such drilling fluids being well known.

Although the feed screw 26 may exert its pressure directly on the chuck 31 or spindle 28, this would require constant screwing down and it is preferred that an intervening spring 41 be provided, so that before the turning of spindle 28 is begun, feed screw 26 may be turned down far enough so that spring 41 will be compressed enough to maintain sufficient pressure on the drill 34 and then on the saw '36 throughout the operation.

After the hole has been completed, the drill press parts can be removed. This could be done by separating the hole saw assembly 33 from the chuck 31 and unscrewing the feed screw 26 all of the way so that it and the remaining parts will slip out. However, removal can be accomplished more easily, if beam 13 is slotted to 35, for example, by loosensing screw 42 and spreading apart the two parts of beam 13 in which the threads cooperating with feed screw 26 are provided. Preferably they should spring apart as screw 42 is loosened, and screw 42 may be tightened to lock feed screw 26 if desired.

Further details At the start of the drilling operation, a punch 43 is placed in chuck 41 instead of hole drill 33. By tapping the top of spindle 28 with the hammer the punch 43 will Patented Mar. 21, 1961 The parts yet to be described will' not ordinarily have been assembled to the beam 13 at 3 produce a punch mark in the upper surface of roof at the proper position for drilling by the twist drill 34. When the punch 43 is removed and the hole saw assembly 33 put in its place, the twist drill 34 will start in the punch mark and drill-its hole through the roof 10.

A plug 44 is provided in hood 22 so that if it is preferred to supply inert gas to the interior of hood 22 a tube may be attached, leading out through the throat 11 to a supply of the inert gas.

The hood 22 preferably has an upstanding sealing ring 46 of rubber-like material, resistant to hydrocarbons, such as neoprene. To ensure proper seating of the sealing ring on the roof, the hood preferably can adjust itself to the roof. To this end, it may be supported by a centered ball and socket connection at 47. It is not necessary for the seal to prevent gas leakage if subjected to substantial pressure, because work of this kind can be done in the earlier part of the day when the contents of the tank are still cool and the pressure is approximately that of the atmosphere.

Seal plates 48 may be laid across collar 12 to close off. the areas thereof not closed by beam 13, and preferably are of a weight to comprise vent valves if the work is delayed and internal pressures approach a dangerous level.

For different lengths of throat 11, alternate bores 49 may be provided for pin 51; and hood 22 may be supported by an adjustable screw 52. Pin 51 may have a drive fit, and may be compressible, as by being hollow and slotted.

I claim:

1. Apparatus for cutting a hole in the roof of a tank containing fuel fumes and having a vent opening therein, including a frame, an arm carried by the frame, means independent of the arm for securing the frame over the opening, said arm being adapted when the frame is thus secured to extend through the opening and approach a point of the roof on the inside of the tank, a hood carried by the arm and having a yieldable rim facing the inside surface of the tank roof, means to adjust the arm from the outside of the tank to press the hood firmly against All the tank roof, and a rotary hole cutter carried by the frame to engage the outer surface of the tank roof opposite the hood to cut through the tank roof wall within the area surrounded by the rim.

2. Apparatus for cutting a hole in a tank containing fumes and having a previous opening therein, including a frame with an arm adapted to extend through the opening from the outside of the tank to the inside of the tank 7 to approach the wall a substantial distance from the opening, a hood at the inner end of the arm having a yieldable rim facing the inside surface of the tank, a hole cutter carried and positioned by the frame to cut through the tank wall toward the area surrounded by the rim, and means for securing the frame to the tank independently of the engagement of the hole cutter with the tank and for pressing the rim against the tank wall.

3. Apparatus for cutting a hole in a tank in accordance with claim 2 in which the hole cutter includes a longitudinally shiftable and rotatable spindle, means for urging the spindle with respect to the frame toward the hood, means for turning the spindle, and a hole-saw carried by the forward end of the spindle.

4. Apparatus for cutting a hole in a tank according to claim 2 in which the yieldable rim is formed of a rubber- -like material.

5. Apparatus for cutting a hole in a tank according to claim 2 and including also an annular dam scalable to the outside of the tank for retaining a quenching medium and through which the hole cutter moves.

References Cited in the file of this patent UNITED STATES PATENTS 1,597,468 Holehouse Aug. 24, 1926 2 ,132,283 Allen Oct. 4, 1938 2,254,792 Brown Sept. 2, 1941 2,380,188 OConnor July 10, 1945 2,704,675 Henderson Mar. 22, 1955 FOREIGN PATENTS 782,274 Great Britain Sept. 4, 1957 

